This invention relates to a phase control mechanism for controlling a predetermined phase relationship of at least one output, and in particular to such a mechanism used in an internal combustion engine for variable valve timing.
Many situations exist in industry and transport where it is necessary to be able to alter the phase relationship between concentric rotating shafts, parallel shafts or other similar elements while they are in motion and under load.
Examples of this need, include the control of the pitch of propellers of aircraft and boats, particularly ships; controlling the pitch of power producing windmills; opening and closing lathe and drill chucks while they are in motion during production runs; controlling the eccentricity of some forms of continuously variable transmissions and determining the valve timing of cam shafts in internal combustion engines.
Operations of the type mentioned above is usually achieved by using electric devices or sliding mechanical mechanisms. These mechanisms all have difficulty with high levels of torque, and in general, with reliability.
A need therefore exists for a mechanical rotating mechanism which is able to alter the phase relationship between two or more concentric or parallel shafts while they are in motion and under load.
The invention may therefore be said to reside in a phase control mechanism for controlling the phase relationship between an input supply and an output, including:
a drive member for coupling with the input supply so as to be driven by the input supply;
at least one first gear coupled to the drive member;
an output element for coupling with the output to provide drive to the output;
at least one second gear in driving engagement with the at least one first gear;
a phase adjusting member;
at least one gear coupled with the phase adjusting member and engaging with the at least one second gear; and
wherein to drive the output, the input supply supplies drive to the drive member to in turn drive the output element and therefore the output via the at least one first gear and the at least one second gear and in order to alter the phase relationship between the input supply and the output, the phase adjustment member is adjusted so that the phase adjusting gear causes the at least one second gear to advance or regress relative to the at least one first gear to thereby change the phase relationship between the output and the drive member and therefore the phase relationship between the input supply and the output.
A further aspect of the invention is specifically directed to controlling the phase relationship between an engine crank shaft and an engine cam shaft to change the cam timing of the engine during operation of the engine.
Mechanisms are known for controlling cam timing to alter the timing of a valve opening in an engine. Such mechanisms generally employ sliding elements and also chains for causing the phase change to occur.
The object of this aspect of the invention is to provide an improvement over those known mechanisms.
The invention may be said to reside in an internal combustion engine including;
a crank shaft for supplying rotary power;
at least one cam shaft for opening and closing valves in the internal combustion engine;
a phase control mechanism coupled between the crank shaft and the at least one cam shaft and having;
(a) a first gear member coupled to the cam shaft;
(b) drive means for transmitting rotary power from the crank shaft to the cam shaft to rotate the cam shaft when the crank shaft rotates;
(c) a phase adjusting means for causing the first gear member to advance or regress; and
means for actuating the phase adjusting means to thereby cause the first gear member to advance or regress to change the phase relationship between the crank shaft and the cam shaft.
Thus, by adjusting the phase adjustment member in an internal combustion engine using the phase control mechanism to control a cam shaft, the phase of the cam shaft relative to the crank shaft of the engine can be adjusted to thereby control the valve time opening during operation of the engine.
Preferably, the input supply comprises a crank shaft of an internal combustion engine and the output comprises a cam shaft in the engine.
Preferably, the drive member is coupled to the crank shaft by gears or by a cam chain for driving the drive member to in turn rotate the cam shaft.
Preferably, the phase adjusting member has actuating means for rotating the phase adjustment member to change the phase relationship between the cam shaft and the crank shaft of the engine.
Preferably, the at least one first gear comprises a bevel gear coupled to the drive member.
Preferably, the at least one second gear comprises a pair of bevel gears rotatably supported on shafts coupled to the output member and preferably the phase adjustment gear comprises a bevel gear meshing with the at least two bevel gears coupled to the output element.
Preferably, the output element comprises a planet cage formed integral with the output.
The invention may also be said to reside in a phase control mechanism for an internal combustion engine for changing the timing between a cam shaft of the internal combustion engine and a crank shaft of the internal combustion engine to thereby vary valve timing within the internal combustion engine, said mechanism including;
a planet cage connectable to the cam shaft;
at least one first bevel gear carried by the planet cage;
an input element couplable to the crank shaft for rotation by the crank shaft;
a second bevel gear carried by the input element and meshing with the first bevel gear carried by the planet cage;
a third bevel gear meshing with the first bevel gear carried by the planet cage;
a phase adjusting means connected to the third bevel gear;
wherein when the mechanism is installed in the engine and the crank shaft is rotated rotation is supplied to the input element to in turn rotate the second bevel gear carried by the input element and the first bevel gear carried by the planet cage so that the planet cage rotates to in turn rotate the cam shaft, and wherein to change the phase relationship and therefore valve timing of the engine, the phase adjusting means is actuated to rotate the third bevel gear so as to advance or regress the first bevel gear connected to the planet cage to advance or regress the planet cage and therefore the cam shaft relative to the crank shaft.
Preferably the phase adjusting mechanism comprises a shaft connected to the third bevel gear, and an actuator for rotating the shaft to in turn rotate the third bevel gear.
Preferably the phase adjusting means maintains the third bevel gear stationary when the cam shaft is required to rotate in phase with the crank shaft.
A still further aspect of the invention provides a clutch mechanism for use with a phase controller for selectively shutting off drive to an output. This aspect of the invention may be said to reside in a clutch mechanism for a phase control mechanism, including:
an input;
an output;
phase control means between the input and the output for controlling a phase relationship;
a rotary member for rotation with the phase control member; and
stop means for selectively stopping rotation of the rotary member so that drive is transmitted to the output for releasing the rotary member for rotation so drive is transmitted to the rotary member rather than to the output to provide a clutching operation between the input and the output.
Preferably, the rotary member comprises a disc and the stop means comprises a disc brake arrangement.